Because coronary atherosclerosis after heart transplantation has been a limiting problem in long-term survival of adults, we reviewed the coronary angiograms, and autopsy data when available, from 21 of 30 children who underwent orthotopic heart transplantation and survived the perioperative period. Six patients had coronary atherosclerosis, and five of these patients died 6 months to 3 years after heart transplantation. The late deaths were sudden and unexpected. Coronary angiography demonstrated several types of lesions, including concentric narrowing, tubular segmental lesions, and abrupt obliteration of major coronary vessels. Risk factors assessed included hypertension, hyperlipidemia, cytomegalovirus infection, type of immunosuppressive regimen, number of rejection episodes, and major histocompatibility antigen mismatches. Only the frequency and duration of rejection episodes seemed to be more prevalent in the patients in whom coronary atherosclerosis developed. Despite the benefits of heart transplantation in treating children with end-stage heart disease, coronary atherosclerosis may limit long-term survival. We suggest that these children should undergo serial coronary angiography to identify those at risk for subsequent events related to coronary artery disease.